"Diagram for conversion of existing telephones to fit new type boxes".
[an undated leaflet that came with a non-approved conversion
kit, and that I copied for future reference. I pass on this
information entirely without any endorsement or support, for
educational value only. It applies to the standard 700-series
type phone that was in general use at the time that modular
sockets were being introduced. I have seen this in use,
including the original bell actually working - contrary to some
informants who said that it had to be changed for a high
impedance bell - but I personally haven't used a phone like
this, and BT won't find one at my house, I assure them ;-) ].
'INSERT MENTAL PICTURE OF RED TRIANGLE HERE'
(1) (2) (3) (4)===(5)===(6) B (7) (8)===(9)
A / ______/
| | C
(10) (11) (12) (13) (14) |(15) |(16)==(17)==(18)==(19)
| | | |
| | | |
green blue red white
(spare)
"Instructions"
A. Remove strap between terminals 4 and 5 and insert 3.3kohm resistor.
B. Remove strap between terminals 6 and 7.
C. Place strap between terminals 17 and 18.
D. Connect line jack cord as shown:
green (spare) to 12, blue to 6, red to 8 and white to 17.
"New type sockets cannot be connected to shared service (party) lines".
(ajf says: party line phones would have been wired slightly
differently anyway, so the above diagram would not help).